水下分散自重构系统虚拟原型

开发了水下分散自重构系统的虚拟原型,从模块、拓扑和构形三个层次对水下分散自重构系统进行了描述,实现了对其运动和自重构过程的动力学仿真,并通过3D方式实时显示仿真与分析结果。利用该虚拟原型分析了系统的多种步态和自重构过程,说明虚拟原型可以为系统自重构策略提供直观可信的设计和测试手段。相对于实物样机,虚拟原型也具有低成本和易扩展的特点。     

基于UG/Motion重型货车主副弹簧悬架动力学仿真分析系统的构建

摘　要：提出了一种基于UG/Motion构建重型货车主副弹簧悬架动力学仿真分析系统的新方法,并应用该方法开发出了相应的软件原型系统。基于两自由度1/4车辆虚拟样机模型,原型系统的仿真分析模块可方便、快捷的实现虚拟样机模型主要设计参数的修改及基于谐波叠加法各种标准等级时域路面不平度的模拟生成。仿真分析模块通过调用UG/Motion集成的RecurDyn解算器来获取仿真分析结果,通过集成Matlab的绘图功能对分析结果进行输出查看;系统的遗传优化设计模块以整个载荷范围内悬挂质量加速度均方根值最小为目标函数,可对悬架的阻尼系数、主副弹簧刚度比和临界载荷比进行了动力学优化。通过一个设计实例验证了原型系统构建的正确性及遗传优化设计模块的有效性。     

人因可靠性仿真

为了改进人因可靠性分析中时间接口、误差传播等方面的不足,进行了人因可靠性仿真方法研究.对仿真中的关键问题如仿真模型建立、仿真流程设计、仿真误差分析和仿真规模确定等进行了深入的理论分析并给出了合理的解决方案.并以核电工程中广为应用的THERP+ HCR方法为原型,给出了人因可靠性仿真的实现实例.仿真结果表明,前述理论分析...     

钢筋混凝土多纵梁渡槽仿真模型试验反演分析

通过仿真模型与原型在弹性和弹塑性阶段的相似比,将钢筋混凝土多纵梁渡槽模型受力性能实测结果反演为原型受力状态。采用三维非线性有限元分析方法,计算了渡槽原型在自重荷载、设计水位荷载、校核水位荷载作用下的受力性能,并与原型反演值进行了对比,证明了渡槽模型试验测得的纵横梁和侧墙截面开裂荷载、应力及渡槽竖向位移和支座反力的合理性,反演计算后可用于正确评价渡槽原型的正常使用受力性能。     

仿蟋蟀切齿叶减阻灭茬刀片设计与试验

为了降低切茬装置切割粉碎玉米根茬所需的功耗,以蟋蟀切齿叶为仿生原型设计了2种仿生灭茬刀片。应用MATLAB软件提取切齿叶部分的轮廓特征,分析其优良的减阻特性,并将此轮廓特征应用于灭茬刀片正刀刃的设计,设计出仿生刀片A;考虑到加工难易程度和经济成本,以二次函数为轮廓特征设计出仿生刀片B。在同等工作参数（前进速度为1 m/s,刀辊转速为420 r/min,耕深为50 mm）前提下,利用ANSYS/LS-DYNA软件仿真和田间试验的方法对2种仿生刀片和原型刀片的载荷状况进行对比分析。仿真结果表明：仿生刀片A和B的最大切削力（分别为881 N和908 N）较原型刀片的最大切削力（1 079 N）分别降低18.35%和15.85%;田间试验结果表明：仿生灭茬刀片A和B的平均扭矩和变异系数分别为267.894 N·m,2.31%和275.843 N·m,2.11%,原型灭茬刀片平均扭矩和变异系数为299.712 N·m和2.33%,且3种灭茬刀片的作业质量（灭茬深度和根茬粉碎率）均可达到相关国家标准。研究结果可为灭茬刀片的减阻降耗设计提供理论指导。     

数控加工仿真环境的建立与应用

近年来,数控加工工艺的发展受到了广泛关注与重视,已经在各个领域得到了很好的应用,尤其在车床数控加工的过程中,取得了良好成效。而对于数控加工而言,仿真软件的应用较为重要,可以通过应用仿真软件进行合理的操作与处理,提升整体加工工作的效果。目前在数控加工仿真软件方面,已经研制出了关于普通数控核心仿真、简单变量编辑以及数控面板操作仿真等类型的技术,基于此,数控加工仿真软件的简介及仿真环境的建立、使用。     

注塑新产品开发中的设计验证

为减少新产品开发中的设计错误,针对技术不确定性假设,综合运用样品技术、实践经验、试验方法、CAD技术、CAE技术,提出了6种设计验证方法.这些方法包括：基于粗略/精确样品的设计验证、基于经验的设计验证、基于实验的设计验证、基于CAD的设计验证、基于加工仿真的设计验证以及基于集成仿真的设计验证.通过注塑制品开发实例,表明这些设计验证方法可应用于新产品开发的概念提出、设计工程、原型测试及试生产阶段.     

国家地震紧急救援训练基地地震废墟结构设计与爆炸成型研究

国家地震紧急救援基地是为了满足实战要求,为地震救援人员提供一个真实的救援训练环境而建立的。其中地震训练废墟是国家地震紧急救援训练基地的核心内容之一。本文给出了地震废墟构筑物A段（板柱结构）的爆炸成型设计流程,对废墟A段进行了原型结构设计和爆炸方案设计。采用ANSYS/LS-DYNA有限元软件建立了该结构的三维有限元实体模型,对其爆炸成型过程进行了仿真分析。通过模拟仿真研究预演了结构爆炸倒塌全过程,得到结构的倒塌型态;并通过爆炸倒塌模拟研究,对原型结构设计的合理性和可行性进行了验证,并对原型结构设计和爆炸成型设计提供了有益的指导。     

基于VERICUT的五轴数控加工仿真研究

通过VERICUT的软件仿真平台,应用UG构建DMU50五轴数控加工机床的仿真模型,并输出驱动数控机床所需要的数控加工代码.针对五轴数控机床加工复杂零件容易发生的碰撞和干涉问题,在VERICUT软件中构建五轴机床,建立刀具库并设置各种关键参数,完成了五轴数控机床的仿真.利用VERICUT的自动比较功能来分析仿真结果,修改数控加工代码并进行机床加工.通过实际加工验证,加工出来的工件全部合格.     

基于VERICUT包装容器模具数控加工仿真及优化技术

在包装容器生产中,关键的是容器模具的加工,而VERICUT是一款既能完成加工仿真又能进行较好优化的三维软件,可实现加工轨迹仿真和机床仿真,图形逼真,而且可通过已有经验数据库来调整各个工序的进给率等参数,提高加工效率,实现NC代码的优化.结合某塑料容器模具的实例展现了VERICUT环境下数控加工仿真及优化的过程,为包装容器模具的生产提供有意的指导.     

Integrated group technology,cell formation,process planning,and production planning with application to the emergency room

In this paper an integrated approach for the formation of parts and machine families in group technology is developed. The integrated approach is used to solve cell formation, process planning, and production planning simultaneously. The given information is part processing sequence, part production volume, part alternative processing plans, and part processing times. The approach is used to determine the machine-part cells and part processing plans, while the total intercell part flow is minimized. Also, the convergence of the algorithm is investigated. The approach goes across and beyond the group technology methods by considering sequencing, production planning, process planning, and part-machine cellular information simultaneously. Two methods are investigated: exact (optimal) and heuristic. The approach first solves an integer programming problem to find processing plans and then uses a procedure to form the machine-part cells. The proposed approach solves the problem iteratively until a set of plans for machine-part cell formations is obtained with minimal intercell part flow or interflow cost. An example is presented to explain the developed approach. Experimental results are also provided. An extension of the approach for solving the operations planning of an emergency room is also covered. In this extension of the approach, the application of cell formation provides a solution to efficiently managing patients and utilizing resources. By grouping patients by their needed medical procedures, time and resource efficiency is accomplished. An application to ER of University Hospitals of Case Western Reserve University is given.     

An experimental method for quantifying tool–part shear interaction during composites processing

The success with which dimensional control during processing of composite structures can be modelled depends on the level of understanding of the underlying mechanisms that drive the accumulation of residual stresses in the part. Tool–part shear interaction during processing can cause substantial warpage in initially flat laminates, yet this phenomenon remains poorly understood. This paper presents an experimental technique in which a thin tool, instrumented with strain gauges, is used for characterizing the interfacial shear stresses that arise between the tool and part during processing. The results show that a sliding interface condition occurs during the majority of the cure cycle, although, at times the tool and part adhere together resulting in high interfacial shear stresses. This tool–part interaction occurs despite the use of a release agent, though the use of a fluoroethylenepropylene (FEP) release film at the tool–part interface reduces the effect.     

车身制件拉延模数字设计研究

为完善车身冲模结构设计的理论体系,提出了制件在冲模设计坐标系中定位的概念,并应用六点定位原理对这一问题进行了研究,探讨了冲压方向的选择原则与工序件的设计方法,根据数字设计的特点对拉延模零件及其特征进行了分类,在此基础上提出了拉延模数字设计的工作策略与方法.结果表明:制件在冲模设计坐标系中的定位是通过设计基准点与冲压方向实现的;拉延模数字设计的工作策略与方法经工程实例验证是可行的.     

Scheduling flexible flow lines with no in-process buffers

An heuristic algorithm is proposed for scheduling a flexible flow line with no intermediate buffers. The line is made up of several processing stages in series, where each stage has one or more identical parallel machines. In the line different part types can be manufactured simultaneously, each of which is processed by at most one machine in every stage. Intermediate queues of parts waiting between the stages for their next operations are not allowed. The problem objective is to minimize the makespan of the schedule for a set of part types selected for processing. The algorithm proposed is a part-by-part heuristic, in which during every iteration a complete processing schedule is determined for one part type selected for loading into the line. The selection of the part type and its complete schedule are based on the cumulative partial schedule obtained for all parts selected so far. The decisions in every iteration are made using a local optimization procedure aimed at minimizing total blocking and waiting time of the machines along the route of the selected part type. The efficiency of the algorithm is tested on several groups of random test problems     

薄壁铝质筒形件加工工艺的研究

通过对给定零件传统加工方案和旋压加工方案的对比分析,从旋压设备、工艺装配和工艺参数等几个方面入手,经实践加工验证,提出了既能保证产品机械性能,又能保证产品质量和精度的旋压加工工艺方案,可以作为典型的旋压加工工艺加以推广。     

Powder Densification Maps in Selective Laser Sintering

Selective Laser Sintering (SLS) is a manufacturing process in which a part is produced without the need for part‐specific tooling. It competes effectively with other manufacturing processes when part geometry is complex and the production run is not large. Traditionally, this was limited to prototype production, although tooling applications are now appearing. This paper describes several applications of powder densification maps to advance solutions in direct SLS of metallic and ceramic powders. Time‐dependent plasticity issues arise in pre‐processing of powder to make it suitable for SLS and in post‐processing of SLS parts to obtain desired density.     

基于模糊Petri网考虑制造约束的零件

加工方案决策是计算机辅助工艺规划中一直未能完全解决的关键问题.首先,在给出Petri网系统和T_不变量定义的基础上,根据Petri网原理和产生式规则建立一个基于模糊规则的零件表面加工方案Petri网模型;然后,根据Petri网T_不变量在考虑制造资源约束的条件下,提出一种新的可选加工方案T_不变量生成方法;最后,通过实例验证了所提方法的有效性.实例结果表明,采用作者提出的决策方法能够获得零件表面加工的最优/次优工艺方案     

Batching and scheduling for a single-machine flexible machining cell with multi-fixturing pallets and controllable processing times

This study addresses an integrated batching and scheduling problem for a single-machine flexible machining cell in which each pallet can load multiple parts, i.e. multi-fixturing pallets, and part processing times can be changed with different processing costs, i.e. controllable processing times. The batching sub-problem is to select the set of parts to be produced in each period of a planning horizon and the resulting scheduling sub-problem is to determine the set of parts to be loaded on each multi-fixturing pallet, the part processing times and the pallet input/processing sequences for the parts selected in each period. A bi-criterion objective is considered that minimises the total tardiness and the total processing cost simultaneously. A solution approach is proposed that consists of three phases from the first to the last period: (a) generating the whole schedule over the planning horizon; (b) selecting the parts to be produced during the current period using the scheduling information; and (c) determining the final schedule for the selected parts. Simulation experiments were done on a number of test instances and the results are reported.     

超声激发振动声成像实验系统的设计

根据超声激发振动声成像的基本原理,设计并构建一个能获得振动声图像的实验系统.该系统由高频信号部分、超声发射及传播部分、低频信号处理和计算机处理与控制等四部分构成.实验表明,该系统能获得生物仿体或软组织内刚性物体的振动声图像,为进行生物组织的振动声成像研究提供了基础;通过采用更高灵敏度的低频水听器和改善共焦换能器的分辨力...